Electric-arc welding or brazing.



G. W. CRAVENS'.

ELECTRIC ARC WELDING 0R BRAZING.

APPLICATION man 1uLY23. 1915.

1,260,875. Patented Mar. 26, 1918.

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UNITED STATES PATENT oEETcE.

GEORGE W. CRAVENS, 0F WESTFIELD, NEW JERSEY, ASSIGNOR T0 C. & C. ELECTRIC & MANUFACTURING COMPANY, 0F GARWOOD, NEW JERSEY, A. CORPORATION 0E NEW JERSEY.

ELECTRIC-ARC WELDING 0R BRAZING.

Specification of Letters Patent.

Application led July 23, 1915. Serial No. 41,469.

To all whom zit may concern:

Be it known that I, GEORGE W. CRAvENs,

`a citizen of the United States, and resident of Westfield, in the county of Union and State of New Jersey, have invented certain new and useful Improvements in Electric- Arc Welding or Brazing, of'which the following is a specification.

This invention relates to the brazing or welding together of metal pieces, through the instrumentality of the electric arc.

The invention is particularly useful in that class of electric welding or brazing wherein the work is one electrode and the other electrode is a metal rod or barv which is fused by the arc and fiows into the joint, the arc being sprung between the bar and the work. In welding by this method the arc having been started, the movable bar constituting one electrode is moved along the joint, the arc heating the parts to be welded and also causing the fusion of the bar itself which flows into the joint and a secure welded or brazed joint is obtained.

In the practice-of this character'of 'welding or brazing, where direct current'is used, the positive electrode develops a much larger amount of heat than the negative electrode. It is necessary, however, that the negative electrode be maintained at a high temperature. This necessitates special constructions or sizes of parts to conserve the cathode heat, when themovable electrode is the cathode.

Where alternating current is employed, the cathodes and anodes respectively of the arc change places many times a second so that substantially equal heats are generated at the work and at the movable electrode. Under such circumstances a relatively inefficient condition results. The alternating current arc is not persistent comparatively speaking, is particularly liable to discontinuance and consequent halting and unevenness of the welded or brazed work results.

According to the present invention the arc is surrounded or inclosed by a nonoxidizing, insulating, .gaseous vapor envelop. This envelop confines the arc, prevents lateral diEusion and dissipation of heat.

The difficulties in the way of the use of an alternating current arc are thus removed so that this character ofarc may be practically and eliciently used. Also with direct current, the electrode may be made the cathode and the heat thereat be so conserved that the necessary high temperature is maintained without unduly restricting the size of the electrode so that there is an abundance of metal for the brazing operation.

Furthermore the envelop prevents access of air to the metal vapors of the arc and, the protecting envelop itself being nonoxidizing, the molten metal and metal vapors which enter into the brazing or welding `are maintained free from oxids so that a clean weld or braze free from these impurities is obtained.

This'gaseous inclosing envelop may be formed by coating the movable electrode with insulating material which is adapted when heated by the arc' to form a non-oxidizing insulating vapor about the arc between the metal of the electrode and the work. The arc having been sprung, the metal conductor will be fused or vaporized and iiow into the weld, but as the conductor is eaten back the edges of the covering will be subjected to the heat of the arc and vaporized to form the envelop. The envelop being thus formed as the conductor is consumed the gaseous envelop is at all times present about the metallic arc.

A coated electrode laid down on the work along the joint to be brazed or welded will not accomplish the desired results for the reason that under such circumstances any vapor which may be formed from the coating will not be carried co-extensively with the are, but at best will only occupy portions of the exterior surface of the metallic arc. To secure the carrying of the nonoxidizing insulating vapor formed from the coating to a distance co-extensive with the metallic are, and the desired inclosure of that arc by the vapor, the movable conductor carrying the coating must be held at an angle to the joint or other work. This angle may vary between 90 and a minimum which may be approximated at 30. The minimum angle at which the desired inclosure is obtained may be considerably less than 30 or it may be more than 30 under some conditions of operation. It

. can be readily ascertained by the operator by placing the electrode so that it makes a very small angle, say 5o, and then gradu- Patented Mar. 26, 1918.

v metals. This is accomplished by coating the metal electrode with the alloying metal and then a coating from which the non-oxidizing arc inclosing vapor is formed may be placed outside this metallic coating. This brings the alloying metal next to the principal metal of the electrode at the arc so that the two metals may become readily intermingled while the vapor envelop is formed outside the whole.

In the accompanying drawings which illustrate the invention,

Figure 1 is a side elevation showing the application of the invention to the welding or brazing of a joint between two horizontal metal plates.

Fig. 2 is an end View of the apparatus shown in Fig. 1.

Fig. 3 is a cross section of the movable electrode.

Fig. 4 is a sectiononpan enlarged scale throu h the arc Showing the relation of the metalic arc and the non-oxidizing vapor envelop and Fig. 5 is a diagram showing the use of direct current:

Referring to the drawings, A and B are two Vflat horizontal plates, for instance of iron, which abut gainst each other at C along which the weld or braze is to be made. The plates are connected by means of clamps `D and E and conductor F with one terminal of an alternating current generator G. The other terminal of the generator is connected by means of a conductor H with themovable electrode I between which and the Work, that is plates A and B, the arc K is formed.

The electrode I comprises a metallic bar or rod 1 upon which is formed a fiuxing coating 2 such as aluminum and outside of that is placed a covering 3 adapted to form a non-oxidizing insulating envelop for the arc when it is vaporized by the heat of the arc. This coating 3 may comprise a Winding of cotton cord saturated w1th powdered plaster of Paris and sodium silicate which serves as a binder added. The cotton cord serves as a carrier for the plaster of Paris and sodium silicate and 1s consumed while the plaster of Paris and silicate are vaporized to form the envelop.

In making the weld .the conductor of the the metal of the movable electrode is transferred to the joint under the action of the arc, the electrode is moved along the joint so that a continuous Weld or braze is secured, the proper angle of theelectrode with the work as before indicated, being maintained.

In Fig. 4 the outer non-oxidlzing envelop is indicated by spiral lines and designated by the numeral 4 and the inclosed metallic are represented by the dotted lines is designated by the reference numeral 5.

Referring now to Fig. 5, the direct current generator L has its positive terminal connected with the work and its negative terminal with the movable electrode I of the same structure as the electrode I. The inclosed arc K similar to K, is drawn between the work and the electrode I', the electrode being held at a proper angle as before indicated. The inclosure of the arc conserves the heat and maintains the necessary hi h temperature at the cathode as before re erred to. While the invention has been illustrated in what is'believed to be its best applications, it may have other applications without departin from its spirit and is not therefore limited t0 the structures shown in the drawin What I c aim is:

1. The method of electric are welding or brazing which consists in establishing a Welding or brazing arc inclosed in an insulating non-oxidizing vapor in welding or brazin proximity to the work.

2. T e method of electric arc welding or brazing which consists in establishing an electric arc between the material to be welded or brazed and an electrode comprising a metal rod covered with an insulating material adapted to be converted by the arc into a non-oxidizing insulating'vapor, said electrode being held out of engagement with and at an an le to the work at which said are is inclose by said vapor.

3. The method of electric arc welding or brazing which consists in establishing an electric arc between the material to be Welded or brazed and an electrode comprising a metal rod covered with an insulating material adapted-to be converted by the arc into a non-oxidizing insulating vapor, said electrode being held out of engagement with no i and at an angle between 5 degrees and the vertical.

4f. The method of electric arc welding or brazing a joint which consistsin estab ishing an electric arc between the material to be Welded or brazed and an electrode comprising a metal rod covered with insulating material adapted to be converted by the arok into a non-oxidizing insulating vapor, moving said electrode alon the joint and during such movement ho ding it out of engagement with the'work and at an angle at which said arc is inclosed by said vapor.

5. The method of electric arc Welding or brazing which consists in establishing an alternating current welding or brazmg are between the work to be weldedor brazed and a movable electrode,'said arc being inclosed in a non-oxidizing insulating vapor.

6. In an arc welding or brazing electrode,

the combination of a metal rod, a coating of a different metal thereon and forming a tubular shell about said rod, and a covering over said coating adapted to produce a nonoxidizing insulating vapor when subjected to the arc.

7. ln an are welding or brazing electrode, the combination with a metal rod 'of a coating of a dierent metal thereon, said metal forming a tubular shell about said metal rod and being in contact therewith, and an insulating covering outside said rod anddifferent metal, said covering being adapted to produce a non-oxidizing insulating vapor whensubjected to the arc.

Signed at New York, in the county of New York and State of New York, this 17th day of July, A. D. 1915. V

GEORGE W.IICRAVENS. 

